Allowance for Credit Losses - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Allowance for Credit Losses
Available for sale debt securities past due	$ 0.0		$ 0.0
Available-for-sale allowance for credit loss	0.0		0.0
Provision (reversal) in allowance on individually evaluated loans	1.7	$ 4.6	7.6	$ 8.0
Provision (reversal) in allowance on collectively evaluated loans	8.5	(7.2)	3.3	(8.6)
Net charge-offs	$ 1.2	$ 0.3	$ 8.6	$ 5.4

Amount of available for sale debt securities past due as of the balance sheet date.

No definition available.

Name:	hth_AvailableForSaleDebtSecuritiesPastDue
Namespace Prefix:	hth_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of net write-offs of financing receivable, charged against allowance for credit loss.

+ References

No definition available.

+ Details

Name:	hth_FinancingReceivableAllowanceForCreditLossWriteoffsNet
Namespace Prefix:	hth_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Increase (decrease) in valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

No definition available.

+ Details

Name:	hth_FinancingReceivableIncreaseDecreaseAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	hth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Increase (decrease) in valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

No definition available.

+ Details

Name:	hth_FinancingReceivableIncreaseDecreaseAllowanceForCreditLossesIndividuallyEvaluatedForImpairment
Namespace Prefix:	hth_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_CreditLossAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant